River Engineering John Fenton Institute of Hydraulic Engineering and Water Resources Management Vienna University of Technology, Karlsplatz 13/222, 1040 Vienna, Austria URL: http://johndfenton.com/ URL: mailto:
[email protected] 1. Introduction 1.1 The nature of what we will and will not do – illuminated by some aphorisms and some people “There is nothing so practical as a good theory” – stated in 1951 by Kurt Lewin (D-USA, 1890-1947): this is essentially the guiding principle behind these lectures. We want to solve practical problems, both in professional practice and research, and to do this it is a big help to have a theoretical understanding and a framework. “The purpose of computing is insight, not numbers” – the motto of a 1973 book on numerical methods for practical use by the mathematician Richard Hamming (USA, 1915-1998). That statement has excited the opinions of many people (search any three of the words in the Internet!). However, numbers are often important in engineering, whether for design, control, or other aspects of the practical world. A characteristic of many engineers, however, is that they are often blinded by the numbers, and do not seek the physical understanding that can be a valuable addition to the numbers. In this course we are not going to deal with many numbers. Instead we will deal with the methods by which numbers could be obtained in practice, and will try to obtain insight into those methods. Hence we might paraphrase simply: "The purpose of this course is insight into the behaviour of rivers; with that insight, numbers can be often be obtained more simply and reliably".